US president Barack Obama to attend G20 summit in Russia

US president Barack Obama has confirmed he will attend the G20 summit in Russia but expressed disappointment the host country had granted temporary asylum to former American intelligence contractor Edward Snowden.

Speaking on NBC's The Tonight Show with host Jay Leno, Mr Obama said Moscow sometimes still slipped into a Cold War mentality.

He did not indicate whether he would attend a separate one-on-one meeting with Russian president Vladimir Putin.

"What I say to President Putin is, that's the past and we've got to think about the future. And there's no reason why we shouldn't be able to cooperate more effectively than we do," Mr Obama said.

The White House had previously said it was evaluating whether that meeting made sense in light of the rift between Washington and Moscow over the Edward Snowden matter.

Relatives of the fugitive American intelligence analyst are reportedly applying for visas to visit him in Russia.

Snowden's whereabouts in Russia are not publicly known after he slipped away from Moscow's international airport last week.

But his lawyer says he has now registered an address within Russian territory and his father is waiting for a visa to visit him.

He says Snowden wanted his father's advice on what to do with his new life.

It is alleged Snowden leaked details of the Obama administration's vast electronic surveillance program which gathers data about emails and phone calls made by American citizens.

Washington had wanted Snowden home to face criminal charges, including espionage for disclosing in June secret American internet and telephone surveillance programs.

"Radical, violent extremism is still out there."

During the interview with Leno, Mr Obama also said the recent threat that caused the US to close embassies throughout the Middle East was significant.

It initially announced the US embassy closures would be only for a day, then extended the closures of some by a week.

"It's a reminder that for all the progress we've made, this radical, violent extremism is still out there," Mr Obama said.

"We've got to stay on top of it."

The US State Department issued a global travel alert last week warning Americans that Al Qaeda may be planning attacks in August, particularly in the Middle East and North Africa.